Plain parameters slower than creating table parameters - sql

Question

I recently discovered the strange behavior, that a function (procedures possibly too) runs significantly slower, when I provide simple NCHAR parameters rather than table value parameters. After trying around a bit I also found, that the function with NCHAR parameters runs as fast as the table value parameter function if I select the NCHAR parameters into a table variable. Here is some code I've created with this.
Function with parameters:
ALTER FUNCTION [rpt].[ReportMaterial]
(
#dateto NCHAR(8),
#mfrnr NVARCHAR(10),
#vkorg NVARCHAR(4)
)
RETURNS #ReturnValue TABLE
(
MANDT NVARCHAR(3),
MATNR NVARCHAR(18),
MFRPN NVARCHAR(40),
MAKTX NVARCHAR(40),
WERKS NVARCHAR(4),
MTART NVARCHAR(4),
KBETR DECIMAL(11, 2),
KONWA NVARCHAR(5)
)
AS
BEGIN
-- FILL UP
SELECT #mfrnr = REPLICATE('0', 10 - LEN(#mfrnr)) + #mfrnr;
-- OUTPUT
WITH mat AS
(
-- direct assignment
SELECT
ma.MANDT,
ma.MATNR,
ma.MFRPN,
mc.WERKS,
ma.MTART
FROM sap.MARA ma
INNER JOIN sap.MARC mc ON ma.MATNR = mc.MATNR AND ma.MANDT = mc.MANDT AND mc.CDCDELETED = 0
INNER JOIN
(
-- better to use in subselect here
SELECT DISTINCT
WERKS
FROM [sap].[Werks] w
WHERE w.WERKSTYPE = 'D' AND w.VKORG = #vkorg
) w ON w.WERKS = mc.WERKS
WHERE ma.MANDT = N'100' AND ma.CDCDELETED = 0 AND ma.MFRNR = #mfrnr
)
INSERT INTO #ReturnValue (MANDT, MATNR, MFRPN, MAKTX, WERKS, MTART, KBETR, KONWA)
SELECT
t.MANDT,
t.MATNR,
t.MFRPN,
mk.MAKTX,
t.WERKS,
t.MTART,
COALESCE(pp.KBETR, 0) KBETR,
pp.KONWA
FROM
(
SELECT
m.MANDT,
m.MATNR,
m.MFRPN,
m.WERKS,
m.MTART
FROM mat m
UNION ALL
-- material selection (part of a hardbundle)
SELECT
ma.MANDT,
ma.MATNR,
ma.MFRPN,
ms.WERKS,
ma.MTART
FROM sap.MARA ma
INNER JOIN sap.MAST ms ON ms.MATNR = ma.MATNR AND ms.STLAN = N'3' AND ms.MANDT = ma.MANDT
INNER JOIN sap.STKO ko ON ko.STLNR = ms.STLNR AND ko.STLAL = ms.STLAL AND ko.MANDT = ms.MANDT
INNER JOIN sap.STPO po ON po.STLNR = ms.STLNR AND po.MANDT = ms.MANDT
INNER JOIN mat mr ON po.IDNRK = mr.MATNR AND mr.MANDT = po.MANDT -- use only relevant items...
INNER JOIN
(
-- better to use as subselect
SELECT DISTINCT
WERKS
FROM [sap].[Werks] w
WHERE w.WERKSTYPE = 'D' AND w.VKORG = #vkorg
) w ON w.WERKS = ms.WERKS
WHERE ma.MTART = N'ZFER' AND ma.MFRNR = N'0080001373' -- we use only dummy hard bundles (sign for mixed manufacturer bundles)
) t
INNER JOIN sap.MAKT mk ON mk.MATNR = t.MATNR AND mk.SPRAS = N'E' AND mk.MANDT = t.MANDT
LEFT JOIN sap.PurchasePrice pp ON pp.MATNR = t.MATNR AND pp.WERKS = t.WERKS AND pp.FLIFN = N'X' AND #dateto BETWEEN pp.VDATU AND pp.BDATU AND #dateto BETWEEN pp.DATAB AND pp.DATBI;
RETURN
END;
Funtion with parameters selected into table variables first:
ALTER FUNCTION [rpt].[ReportMaterial]
(
#dateto NCHAR(8),
#mfrnr NVARCHAR(10),
#vkorg NVARCHAR(4)
)
RETURNS #ReturnValue TABLE
(
MANDT NVARCHAR(3),
MATNR NVARCHAR(18),
MFRPN NVARCHAR(40),
MAKTX NVARCHAR(40),
WERKS NVARCHAR(4),
MTART NVARCHAR(4),
KBETR DECIMAL(11, 2),
KONWA NVARCHAR(5)
)
AS
BEGIN
-- FILL UP
SELECT #mfrnr = REPLICATE('0', 10 - LEN(#mfrnr)) + #mfrnr;
--> Better performance if using a table to join instead of directly using of parameters
-- CREATE TABLE
DECLARE #keyValue TABLE
(
MFRNR NVARCHAR(10),
VKORG NVARCHAR(4)
);
INSERT INTO #keyValue (MFRNR, VKORG) VALUES (#mfrnr, #vkorg);
-- OUTPUT
WITH mat AS
(
-- direct assignment
SELECT
ma.MANDT,
ma.MATNR,
ma.MFRPN,
mc.WERKS,
ma.MTART
FROM sap.MARA ma
INNER JOIN sap.MARC mc ON ma.MATNR = mc.MATNR AND ma.MANDT = mc.MANDT AND mc.CDCDELETED = 0
INNER JOIN
(
-- better to use in subselect here
SELECT DISTINCT
WERKS
FROM [sap].[Werks] w
INNER JOIN #keyValue kv1 ON kv1.VKORG = w.VKORG
WHERE w.WERKSTYPE = 'D'
) w ON w.WERKS = mc.WERKS
INNER JOIN #keyValue kv2 ON kv2.MFRNR = ma.MFRNR
WHERE ma.MANDT = N'100' AND ma.CDCDELETED = 0
)
INSERT INTO #ReturnValue (MANDT, MATNR, MFRPN, MAKTX, WERKS, MTART, KBETR, KONWA)
SELECT
t.MANDT,
t.MATNR,
t.MFRPN,
mk.MAKTX,
t.WERKS,
t.MTART,
COALESCE(pp.KBETR, 0) KBETR,
pp.KONWA
FROM
(
SELECT
m.MANDT,
m.MATNR,
m.MFRPN,
m.WERKS,
m.MTART
FROM mat m
UNION ALL
-- material selection (part of a hardbundle)
SELECT
ma.MANDT,
ma.MATNR,
ma.MFRPN,
ms.WERKS,
ma.MTART
FROM sap.MARA ma
INNER JOIN sap.MAST ms ON ms.MATNR = ma.MATNR AND ms.STLAN = N'3' AND ms.MANDT = ma.MANDT
INNER JOIN sap.STKO ko ON ko.STLNR = ms.STLNR AND ko.STLAL = ms.STLAL AND ko.MANDT = ms.MANDT
INNER JOIN sap.STPO po ON po.STLNR = ms.STLNR AND po.MANDT = ms.MANDT
INNER JOIN mat mr ON po.IDNRK = mr.MATNR AND mr.MANDT = po.MANDT -- use only relevant items...
INNER JOIN
(
-- better to use as subselect
SELECT DISTINCT
WERKS
FROM [sap].[Werks] w
INNER JOIN #keyValue kv1 ON kv1.VKORG = w.VKORG
WHERE w.WERKSTYPE = 'D'
) w ON w.WERKS = ms.WERKS
WHERE ma.MTART = N'ZFER' AND ma.MFRNR = N'00000000'
) t
INNER JOIN sap.MAKT mk ON mk.MATNR = t.MATNR AND mk.SPRAS = N'E' AND mk.MANDT = t.MANDT
LEFT JOIN sap.PurchasePrice pp ON pp.MATNR = t.MATNR AND pp.WERKS = t.WERKS AND pp.FLIFN = N'X' AND #dateto BETWEEN pp.VDATU AND pp.BDATU AND #dateto BETWEEN pp.DATAB AND pp.DATBI;
RETURN
END;
Does anybody have an Idea, why this is the case? Do I need to leverage this effect by allways selecting parameters into temporary tables/table variables?